1. Field of Invention
The invention is directed to tools for retrieving an object disposed in the bore of a well, and in particular, to overshot fishing tools.
2. Description of Art
It is common for objects such as tools and broken segments of pipe to become forcibly lodged within the wellbore of an oil or gas well. In order for these objects to be removed from the wellbore, various fishing tools have been developed for the purpose of latching onto and retrieving the object, referred to in the industry as the “fish,” from the wellbore. One type of fishing tool functions by gripping onto the outer surface, e.g., the outer diameter of a segment of pipe, of the fish. These types of fishing tools are referred to as “overshot” fishing tools. Other types of fishing tools that function by gripping the lumen of the fish, e.g., the inner diameter of a segment of pipe of the fish.
Regardless of type of fishing tool, after the fish is gripped by the fishing tool, the fishing tool and the fish are transported to the surface of the well. These prior fishing tools, however, are cumbersome to operate and are not designed to grab and retrieve different types of fish. For example, some fishing tools are only able to grab and retrieve fish that are pipe segments. Other fishing tools are only able to grab and retrieve objects having an outer diameter that falls within a narrow range. For example, most known overshot fishing tools cannot retrieve fish having a variation in size of more than 1/16th of an inch. In other words, if a fish is believed to have an outer diameter of 2 inches, a corresponding overshot fishing tool is capable of grabbing the fish if the actual outer diameter is within the range of 2 1/16 inches and 1 15/16 inches. A fish having a larger or smaller outer diameter cannot be grabbed by the prior art fishing tool.
Additionally, prior art overshot fishing tools provide axial and radial loading on the fish and on the housing of the fishing tool, without any circumferentially loading. Such overshot fishing tools that load axially and radially, without circumferentially loading, are limited as to the size and weight of the fish that can be retrieved.